DE69809425T2 - EXTENDABLE LADIES 'LINK IN MANY DIRECTIONS - Google Patents

Abstract

Multi-directionally extensible absorbent articles for wearing in an undergarment, such as sanitary napkins, panty liners, incontinence pads, and the like, are disclosed. Multi-directionally extensible absorbent cores, and omni-directionally extensible absorbent cores for such absorbent articles are also disclosed. The absorbent articles with the omni-directionally extensible absorbent core are provided with an overall diagonal extensibility to accommodate the forces exerted on the absorbent article by the wearer's undergarments when the wearer walks, and otherwise moves about. The absorbent articles may also be provided with regions of extensibility that are oriented in certain directions to reduce the forces acting on the absorbent article when worn.

Description

FIELD OF INVENTION

The present invention relates to absorbent articles such as sanitary napkins, panty liners, incontinence devices and the like. In particular, the present invention relates to absorbent articles of the above type which are stretchable and preferably elastically stretchable in multiple directions.

BACKGROUND OF THE INVENTION

Absorbent articles such as sanitary napkins, panty liners and incontinence pads are designed to absorb and retain fluid and other excretions from the human body and prevent soiling of the body and clothing. The sanitary napkins are a type of absorbent article worn by women that is usually positioned between the legs of the wearer, adjacent to the perineal area of the body.

Typically, most of the disposable absorbent articles of the type mentioned above are made from materials that do not stretch. That is, the materials (and the article itself) do not stretch under the forces that the absorbent article is normally subjected to when worn.

The inability of absorbent articles to stretch causes such articles to have a number of serious disadvantages. One of the most serious is that they are not as comfortable for the wearer as they could be. The wearer should ideally be able to notice a difference between an absorbent article that stretches to conform to the wearer's body and with the wearer's movement and an absorbent article that does not stretch. Conventional sanitary napkins also lack the ability to stretch and move with the wearer's underwear, which sanitary napkin to shift within the wearer's underwear. Providing the sanitary napkin with stretch properties will allow the sanitary napkin to better conform to the wearer's underwear and stay in place.

Several patent publications disclose absorbent articles with various components capable of stretching. Such efforts are described in US Patent 2,801,567 issued to Smith, US Patent 3,570,493 issued to Olsson, US Patent 3,653,382 issued to Easley et al., US Patent 3,717,150 issued to Schwartz, US Patent 4,013,816 issued to Sabee et al., US Patent 4,041,949 issued to Kozak, US Patent 4,166,464 issued to Korpman, US Patent 4,533,357 issued to Hall, US Patent 4,573,991 issued to Pieniak et al., US Patent 4,578,070 issued to Holtman, US Patent 4,596,570 issued to Jackson et al., US Patent 4,655,760 issued to Morman et al., US Patent 4,731,066 issued to Korpman, US Patent 4,847,134 issued to Fahrenkrug et al., US Patent 4,891,258 issued to Fahrenkrug et al., US Patent 4,965,122 issued to Morman, US Patent 4,992,324 issued to Dube, US Patent 5,011,480 issued to Gossens et al. and European Patent Application 0 450 541 A2 issued in the name of Morris et al. US 5,288,791 also discloses nonwoven substrates with elastic behavior under low stresses.

Some of the publications listed above disclose providing absorbent articles having one or more stretchable components. More recently, various embodiments of absorbent articles, such as sanitary napkins, that are composed entirely of components capable of stretching to accommodate the movements of the wearer and the wearer's undergarments were disclosed in U.S. Patent 5,611,790, entitled "Stretchable Absorbent Articles," issued to Osborn et al. on March 18, 1997. Improved Materials for Use in Absorbent Articles have also been developed. WO 93/01786, also published to Osborn, discloses stretchable absorbent articles.

For example, U.S. Patent 5,518,801, entitled "Web Materials Exhibiting Elastic-Like Behavior," issued to Chapell et al. on May 21, 1996, discloses web materials exhibiting elastic-like behavior and absorbent articles using such materials. U.S. Patent 5,560,878, entitled "Method and Apparatus for Making Stretchable Absorbent Articles," issued to Dragoo et al. on October 1, 1996, discloses a stretchable absorbent material. PCT Publication No. WO 95/20931, entitled "Absorbent Articles," issued in the name of Osborn et al. on August 10, 1995, is directed to stretchable absorbent articles provided with improved mechanisms for maintaining the articles in contact with the wearer's body. However, the search for improved variations of stretchable absorbent articles and absorbent cores for such absorbent articles has continued.

It is therefore an object of this invention to provide an improved absorbent article, such as a sanitary napkin, which is capable of stretching, or, more preferably, one which is elastically stretchable.

It is a further object of this invention to provide an absorbent article, such as a sanitary napkin, that is capable of elastically stretching in multiple directions.

It is a further object of the present invention to provide stretchable absorbent articles provided with improved mechanisms for preventing some of the problems affecting such substantially highly flexible absorbent articles, such as the undesirable tendency of the end regions of the absorbent articles to fold over onto the remainder of the absorbent article.

It is a further object of the present invention to provide a stretchable absorbent article having a diagonal stretchability to accommodate the forces of walking and similar movements exerted on the absorbent article when attached to the wearer's undergarment.

It is a further object of the present invention to provide improved absorbent cores for stretchable absorbent articles.

It is a further object of the present invention to provide an absorbent article having side flaps or wings that are stretchable to relieve stress in the sanitary napkin when the flaps are placed around the side edges of a wearer's undergarments.

It is yet another object of the present invention to provide a stretchable absorbent article having an improved form of stretchable crimp seal that connects the stretchable components of the absorbent article together and still allows them to stretch.

These and other objects of the present invention will be more readily understood when considered with reference to the following description and in conjunction with the accompanying drawings.

SUMMARY OF THE INVENTION

The present invention provides a multidirectionally stretchable and preferably elastically stretchable absorbent article for wear in an undergarment such as a sanitary napkin, a panty liner, an incontinence device or the like.

The multidirectional stretchable absorbent article has a longitudinal centerline, a transverse centerline, a pair of longitudinal side edges, a pair of end edges, a first end region, a second end region, and a central region between the first and second end regions. The multidirectionally stretchable absorbent article preferably has a main body portion comprising at least two regions stretchable in different directions, and at least one of those regions, and preferably two or more of those regions, are capable of elongation of 25% under forces of less than or equal to about 500 grams. The main body portion of the multidirectionally stretchable absorbent article preferably comprises a multidirectionally stretchable liquid pervious topsheet, a multidirectionally stretchable liquid impervious backsheet at least partially circumferentially joined to the topsheet, and a multidirectionally stretchable absorbent core positioned between the topsheet and the backsheet.

In a preferred embodiment, the main body portion of the multidirectionally stretchable absorbent article has a central region that is stretchable primarily in the transverse direction. The first and second end regions each preferably comprise three regions of stretchability: a first region of stretchability, a second region of stretchability, and a third region of stretchability. The first region of stretchability in the end regions is located along at least a portion of the longitudinal centerline adjacent one of the end edges of the main body portion. The first region of stretchability is preferably stretchable in the transverse direction. The second region of stretchability is located laterally outward of at least a portion of the first region of stretchability on one side of the first region of stretchability and extends toward one of the longitudinal side edges of the absorbent article. The second region of stretchability is stretchable in a direction intermediate the longitudinal direction and the transverse direction. The third region of extensibility is disposed laterally outwardly of at least a portion of the first region of extensibility on the other side of the first region of extensibility. The third region of extensibility extends toward the other longitudinal side edge of the absorbent article and is stretchable in a direction which lies between the longitudinal and transverse directions.

In this or other embodiments, the multidirectionally stretchable absorbent article may be provided with side flaps or wings that extend laterally outward beyond the longitudinal side edges of the main body portion of the absorbent article. The side flaps have an improved configuration of regions therein that are stretchable to relieve stress on the flaps when placed around the side edges of a wearer's undergarments. In particular, the side flaps are integral with the main body portion and are provided with stretchability in zones located inboard of the edge of the absorbent core of the absorbent article. It is also within the scope of the present invention for the flaps described herein to be used on conventional, non-stretchable absorbent articles.

In addition, the components forming the stretchable absorbent article are preferably held together by using a novel, liquid-impermeable gasket having a sinusoidal configuration that allows the components to stretch elastically.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a plan view of a preferred embodiment of a sanitary napkin of the present invention.

Fig. 2 is a side cross-sectional view taken along line 2-2 of Fig. 1 through the corner region of one of the flaps of the sanitary napkin.

Fig. 3 is a side cross-sectional view taken along line 3-3 of Fig. 1 through the central region of one of the flaps.

Fig. 4 is a bottom view of the sanitary napkin shown in Fig. 1, which is illustrated with the extensible network regions omitted from the backsheet for simplicity of illustration.

Fig. 5 is a simplified plan view of a sanitary napkin after a stretching process.

Figure 6 is a schematic side view of a flexible and stretchable sanitary napkin showing some of the problems that the sanitary napkin may experience if it is not provided with the improved features of the present invention.

Figure 7 is a plan view of a preferred composite sanitary napkin according to the present invention.

Fig. 8 is a cross-sectional view of the assembled sanitary napkin shown in Fig. 7 taken along line 8-8 and shown without corrugations in the topsheet and backsheet for simplicity.

DETAILED DESCRIPTION OF THE INVENTION

Figures 1-4 show a preferred embodiment of a disposable absorbent article of the present invention. The present invention relates to absorbent articles worn in an undergarment such as a sanitary napkin, panty liners, incontinence devices and the like.

The term "absorbent articles" as used herein refers to articles which absorb and contain body exudates. In particular, the term refers to articles which are placed on or near the body of the wearer to absorb the various exudates emitted by the body. The term "absorbent articles" is intended to include sanitary napkins, panty liners and incontinence pads (and other articles worn in the crotch region in the lingerie).

The term "disposable" refers to articles that are intended to be discarded after a single use and preferably recycled, composted or otherwise disposed of in an environmentally acceptable manner. (That is, they are not intended to be laundered or otherwise remanufactured or reused as absorbent articles.) In the preferred embodiment shown, the absorbent article is a sanitary napkin designated 20.

The term "sanitary napkin" as used herein refers to an article worn by women adjacent to the pubic region that is intended to absorb and contain the various exudates emitted by the body (e.g., blood, menstrual fluids, and urine). However, the present invention is not limited to specific types or configurations of absorbent articles as shown in the drawings.

The sanitary napkin 20 has two surfaces, a body-contacting surface or "body-facing surface" 20A and a garment-facing surface 20B. The sanitary napkin 20 is shown in Figure 1 as viewed from its body-facing surface 20A. The body-facing surface 20A is intended to be worn adjacent to the wearer's body. The garment-facing surface 20B is intended to be positioned adjacent to the wearer's undergarments when the sanitary napkin 20 is worn.

The sanitary napkin 20 has two centerlines, a major longitudinal centerline (or "longitudinal centerline") L and a major transverse centerline (or "transverse centerline") T. The term "longitudinal" as used herein refers to a line, axis or direction in the plane of the sanitary napkin 20 which in the substantially aligned with (e.g., approximately parallel to) a vertical plane which divides a standing wearer into left and right halves of the body when the sanitary napkin 20 is worn. As used herein, the terms "transverse" and "lateral" are interchangeable and refer to a line, axis or direction which lies within the plane of the sanitary napkin 20 and which is substantially perpendicular to the longitudinal direction.

As shown in Fig. 1, the sanitary napkin 20 preferably includes a main body portion 22 and two flaps 24. Fig. 1 shows that the main body portion 22 of the sanitary napkin 20 includes the portion of the sanitary napkin without the flaps 24. The main body portion 22 has two spaced apart longitudinal edges 26, two spaced apart transverse or end edges (or "ends") 28, which together form the perimeter 30 of the main body portion. The main body portion 22 has four corners 27 at which the longitudinal edges 26 and end edges 28 converge. The main body portion 22 also has two end regions, designated first end region 32 and second end region 34. A central region 36 is located between the end regions 32 and 34. The end regions 32 and 34 extend longitudinally outwardly from the edges of the central region 36 by 1/8 to about 1/3 or more of the length of the main body portion. A detailed description of the characteristics of a central region and two end regions for a sanitary napkin is contained in U.S. Patent 4,690,680 issued to Higgins on September 1, 1987.

The main body portion 22 of the sanitary napkin 20 may be of any thickness, including relatively thick, medium thick, relatively thin, or even very thin (or "ultra thin"). The properties of substantially non-stretchable "ultra thin" sanitary napkins are described in U.S. Patents 4,950,264 and 5,009,653 issued to Osborn. The embodiment of the sanitary napkin 20 shown in Figures 1-3 of the drawings is intended to be an example of an ultra thin sanitary napkin having a thickness of about 4 millimeters. The main body portion 22 of the sanitary napkin 20 is also preferably relatively flexible so that it is comfortable for the wearer.

The sanitary napkin 20 shown in the drawings is extensible, preferably stretchable, and more preferably elastically stretchable in multiple directions. The term "stretchable" as used herein refers to articles that can stretch in at least one of their dimensions in the X-Y plane. The X-Y plane is a plane substantially parallel to the surfaces of the sanitary napkin 20. The term "stretchable" includes articles that are stretchable and elastically stretchable. The term "stretchable" as used herein refers to articles that are stretchable when stretching forces are applied to the articles and offer some resistance to a stretching action.

The terms "elastically stretchable" or "elastically extensible" are intended to be synonymous. These terms are illustrated with the simplified schematic view of the sanitary napkin in Fig. 5. As seen in Fig. 5, the sanitary napkin 20 can stretch to a stretched length LS and a stretched width WS. As used herein, the terms "elastically stretchable" or "elastically extensible" mean that when the stretching forces designated "F" are removed, the sanitary napkin tends to return to its unstretched or unstretched dimensions (or "original" dimensions LU and WU). The sanitary napkin 20 does not have to return all the way to its unstretched dimensions. It can return to relaxed dimensions (such as LR and WR) between its unstretched dimensions (LU and WU) and its stretched (or stretched) dimensions LS and WS, as shown in Fig. 5.

Fig. 2 shows the individual components of the main body portion 22 of the sanitary napkin 20 of the present invention. The main body portion 22 of the sanitary napkin preferably comprises at least three primary components. These include a liquid permeable topsheet 38, a liquid impermeable backsheet 40 and an absorbent core 42 disposed between the topsheet 38 and the backsheet 40. The liquid pervious topsheet, liquid impervious backsheet and absorbent core may comprise a number of suitable materials provided they are extensible as described below or comprise base materials capable of being modified as specified herein to provide them with extensibility.

In the embodiment shown in Figure 1, the base material for the liquid permeable topsheet 38 comprises an apertured formed film. Suitable formed films are described in U.S. Patent No. 3,929,135 issued to Thompson on December 30, 1975; U.S. Patent No. 4,324,245 issued to Mullane et al. on April 13, 1982; U.S. Patent No. 4,342,314 issued to Radel et al. on August 3, 1982; U.S. Patent No. 4,463,045 issued to Ahr et al. on July 31, 1984 and U.S. Patent No. 5,006,394 issued to Baird on April 9, 1991. A particularly preferred base material for the topsheet 38 comprises a molded film described in one or more of the above patents and marketed on sanitary napkins by The Procter and Gamble Company of Cincinnati, Ohio as a "DRI-WEAVE" topsheet. The base material for the topsheet 38 preferably has a hydrophilic surfactant incorporated therein during manufacture. The base material for the topsheet 38 is modified to be multidirectionally stretchable, as discussed in more detail below.

The absorbent core 42 may comprise a variety of absorbent materials that are capable of stretching or are capable of being modified to become stretchable. For example, materials suitable for use as the absorbent core 42 could comprise a knit material or a nonwoven material that is modified to make it multi-directionally stretchable. The term "multi-directionally" stretchable as used herein refers to being stretchable in at least two directions in the XY plane. (It should be understood, therefore, that the materials described herein are suitable for use in the absorbent core 42.) Core 42 may optionally be used as absorbent cores in other types of disposable absorbent articles, such as disposable diapers and the like, if desired.)

A suitable multidirectional elastically stretchable nonwoven material is a 50/50 blend of polymeric fibers, such as polyester fibers, and a fibrous superabsorbent hydrogel-forming polymeric material (or "absorbent gelling material"). A suitable fibrous absorbent gelling material is available as Product #1161 from Camelot Superabsorbents, Ltd. of Calgary, Alberta, Canada. The nonwoven material is preferably embossed with the pattern described in U.S. Patent 4,781,710 issued to Megison et al. The embossed nonwoven material is then preferably heated to a temperature just below the glass transition temperature of the polyester (about 280ºF (about 138ºC)) and laterally consolidated as described in University of Tennessee U.S. Patent 5,244,482 entitled "Post-Treatment of Nonwoven Webs" issued to Hassenboehler, Jr. et al. on September 14, 1993, so that it is stretchable in a first direction.

The nonwoven web is then preferably cooled to about 200°F (about 93°C) and mechanically compressed (or "micrext") to impart extensibility in a second direction perpendicular to the first direction. Suitable methods for mechanically compressing nonwoven webs are described in U.S. Patent 3,260,778 issued to Walton on July 12, 1966; U.S. Patent 3,426,405 issued to Walton on February 11, 1969; and U.S. Patent 5,117,540 issued to Walton et al. on June 2, 1992. The entire process can produce a nonwoven absorbent core material that shrinks about 25% in both the machine direction (the direction in which the fabric unwinds from a roll in the process of manufacturing the sanitary napkin 20) and the cross machine direction (perpendicular to the direction of unwinding) under forces of less than or equal to about 200 grams/inch (about 80 g/cm), preferably less than or equal to about 100 grams/inch (about 40 g/cm), more preferably between about 25 to about 100 grams/inch (about 10 to 40 g/cm) and most preferably about 60 grams/inch (about 24 g/cm).

The absorbent core 42 in the embodiment shown in the drawings preferably comprises an omnidirectionally elastically extensible knit material. The phrase "omnidirectionally" extensible as used herein refers to extensibility in devices in the X-Y plane. In a particularly preferred embodiment, the absorbent core 42 is a laminate of two or more knit materials. Preferably, the absorbent core 42 comprises a three-layer structure having layers of knit nylon material, knit polyester material and knit 20/1 acrylic material needle stitched together, giving the laminate a quilted jacquard pattern. One such material is known as Product No. B7112 and is available from Flynt Amtex, Inc. of Burlington, NC. The Flynt material has a basis weight of 24 mg/cm2, an absorption capacity of greater than or equal to about 5 grams of water per gram of fabric, and a thickness of about 2 mm. A simple test for determining the capacity of such a material is described below in the Test Methods section.

The absorbent core 42 (e.g., the Flynt material) is preferably capable of omnidirectional elongation in the following amounts at the specified forces: 5% elongation under a force of less than or equal to about 20 grams/inch (about 8 g/cm); 10% elongation under a force of less than or equal to about 35 grams/inch (about 14 g/cm); 25% elongation under a force of less than or equal to about 200 grams/inch (about 80 g/cm), preferably less than or equal to about 100 grams/inch (about 40 g/cm), more preferably less than or equal to about 85 grams/inch (about 33 g/cm), and 50% elongation under a force of less than or equal to about 225 grams/inch (about 90 g/cm). All forces specified here are measured using a one inch (2.54 cm) wide strip of absorbent material as described in the Test Procedure section below. For simplicity, omnidirectional extensibility is measured using Use of strips cut lengthwise, crosswise and at a 45 degree diagonal.

The absorbent core 42 (e.g., the Flynt material) is preferably omnidirectionally elastically extensible. The absorbent core 42 may, but need not, return a full distance to its unstretched dimensions when the stretching forces are removed. The characteristic may be expressed in terms of percent (%) set of the core material. The Flynt material has less than or equal to about 10% set in the longitudinal direction, the transverse direction, and the diagonal direction.

The absorbent core 42 (e.g., the Flynt material) is preferably highly flexible and collapsible. The Flynt material has a Taber stiffness of about 0.11 or 0.12 g cm; a flexural strength of about 26 mg cm/cm and a bending resistance of about 14 or 15 grams, measured on the Flynt material alone using the test set forth in U.S. Patent 5,009,653 issued to Osborn. The Flynt material has one side with a "puffy" appearance and one side which is relatively flat. The Flynt material can be placed in the sanitary napkin 20 with both sides adjacent to the topsheet 38. No modification of this absorbent core material is necessary since it is inherently omnidirectionally stretchable.

In certain cases, it may be desirable to provide the flynt material with additional absorbent capacity for use as the absorbent core 42. This may be done in a number of non-limiting ways. In one embodiment, the surface of the additional web or strip of stretchable material which is disposed adjacent to the flynt material (i.e., its inside surface) may have the absorbent gelling material disposed thereon. The additional web or strip therefore "catches" or holds the absorbent gelling material adjacent to the underside of the flynt material.

In a preferred version of such an embodiment, the stretchable material comprises a rectangular strip about 2 inches (about 5 cm) wide and about 6.25 inches (about 16 cm) long of a through-air bonded nonwoven material composed of bicomponent fibers manufactured under the trade name HAVIX 52146 by Havix Corporation, Gifu City, Japan. The HAVIX material has a degree of stretchability in one direction, which is preferably its width direction. The HAVIX material is preferably mechanically compressed (or "micrext") as described in connection with the multidirectionally stretchable nonwoven material discussed above so that it is also stretchable in the length direction. The absorbent gelling material is preferably applied to the HAVIX material as a mixture of Nalco 1180 absorbent gelling material available from Nalco Chemical Company, Naperville, IL, and PEGOSPERSE surfactant available from Lonze, Inc., Williamsport, PA. These components are preferably mixed together in a ratio of about 10 grams of the absorbent gelling material to about 1 gram of the surfactant. Preferably, about 0.3 to about 0.4 grams of this material is applied to the strip of HAVIX material.

The strip of HAVIX material may be bonded to the bottom surface of the Flynt material in any suitable manner. Preferably, the HAVIX material is stretched and bonded to the bottom surface of the Flynt material using an adhesive such as adhesive number 2031 manufactured by Findley Adhesive Company of Wauwatosa, Wisconsin. A double-sided adhesive strip may be applied around the perimeter of the HAVIX material for attachment to the Flynt material if additional security is desired. The use of the additional sheet of material with the absorbent gelling material preferably nearly doubles the absorbent capacity of the sanitary napkin 20 from a total capacity of about 12 grams to about 23 grams. The Absorption capacities are preferably measured according to the test set forth in U.S. Patent 5,009;653 issued to Osborn.

In other embodiments, the absorbent core 42 may be provided with additional capacity in other ways. For example, instead of adding a strip of material to the bottom of the absorbent core as described above, the absorbent gelling material could be added to the surface of one or more layers of the absorbent core (such as one of the different layers of the flynt material). Alternatively, one or more of the layers of the absorbent core could comprise at least in part a fibrous absorbent gelling material.

The backsheet 40 may be any suitable liquid impervious material that is extensible or has a base material that can be modified to provide extensibility as specified herein. Preferably, the material for the backsheet 40 is a polyethylene film having a thickness of about 0.012 mm (0.5 mil) to about 0.015 mm (2.0 mil). Exemplary polyethylene films are manufactured by Clopay Corporation of Cincinnati, Ohio under the designation P 18-0401 and microflex 1401. The backsheet 40 may be embossed or matte to provide a more cloth-like appearance. Further, the backsheet 40 may allow vapors to escape from the absorbent core 42 (i.e., it may be breathable) while still preventing exudates from passing through the backsheet. In a preferred embodiment, when the base material for the backsheet 40 is prepared, it is subjected to a corona discharge treatment to assist in adhering the desired areas thereof to the topsheet. Methods of treating a film material with a corona discharge are described in US Patents 4,351,784, 4,456,570 and 4,535,020 issued to Thomas et al. The base material for the backsheet 40 is modified to make it multidirectionally stretchable, as discussed in more detail below.

The topsheet 38, backsheet 40 and absorbent core 42 can be assembled together in a variety of configurations known in the art (including layered or "sandwich" configurations and wrapped or "tube" configurations). Figures 1-4 show a preferred embodiment of the sanitary napkin 20 assembled together in a sandwich construction in which the topsheet 38 and backsheet 40 have a length and width dimension that is significantly greater than that of the absorbent core 42. The topsheet 38 and backsheet 40 extend beyond the edges of the absorbent core 42 to form portions of the perimeter 30. The topsheet 38 is preferably joined to the bodyside side of the absorbent core 42. The topsheet 38 may be joined to the absorbent core 42 in any suitable manner known in the art for this purpose, such as by an open pattern of adhesives. The backsheet 40 need not be, and in the illustrated embodiment is preferably not, joined to the absorbent core 42. The portions of the topsheet 38 and the backsheet 40 that extend beyond the edges of the absorbent core 42 to form the perimeter 30 are preferably joined together, as described in more detail below.

The topsheet 38 may be joined to the absorbent core 42 by a uniform continuous layer of adhesive, a patterned layer of adhesive, or an array of separate lines, spirals, or dots of adhesive. One adhesive which has been found satisfactory for this purpose is manufactured by Findley Adhesive Company of Wauwatosa, Wisconsin as Adhesive No. 2031. The adhesive is preferably applied in an open network pattern of filaments of adhesive as disclosed in U.S. Patent 4,573,986 entitled "Disposable Waste-Containment Garment" issued to Minetola et al. on March 4, 1986. Other exemplary open network patterns of adhesive filaments having multiple lines of adhesive filaments intertwined in a spiral pattern are by the apparatus and methods shown in U.S. Patent 3,911,173 issued to Sprague, Jr. on October 7, 1975; U.S. Patent 4,785,996 issued to Ziecker et al. on November 22, 1978; and U.S. Patent 4,842,666 issued to Werenicz on June 27, 1989. Alternatively, the components of the sanitary napkin may be joined by thermal bonds, pressure bonds, ultrasonic bonds, dynamic mechanical bonds, or any other suitable attachment means or combinations of these attachment means as are known in the art.

The entire sanitary napkin 20 or regions thereof may be extensible in various directions. The multidirectionally extensible absorbent article preferably has a main body portion comprising at least two regions extensible in different directions, and at least one of these regions, and preferably two or more of these regions, are capable of elongation of 25% under forces of less than or equal to about 500 grams. In the embodiment shown in Figures 1-4, the central region 36 of the sanitary napkin 20 is substantially extensible in the transverse direction. This is generally the direction of the arrows shown in Figure 1. As shown in the drawings, if the sanitary napkin 20 is provided with flaps 24, the extensibility of the central region 36 may extend into the flaps 24. The central region 36 expands laterally to assist the flaps 24 in folding around the curved side edges of the wearer's undergarment.

As used herein, the term "substantially in the transverse direction" (or substantially in another direction) means that a major component of the extensibility is in the direction specified. However, the total extensibility need not be exactly in the direction specified. Therefore, if the extensibility is to be substantially in the transverse direction, the extensibility need not be exactly parallel to the main transverse centerline of the sanitary napkin. However, the extensibility is preferably oriented more in the transverse direction than in the longitudinal direction.

The first and second end regions 32 and 34 of the sanitary napkin 20 shown in Figures 1-4 each preferably include three regions of extensibility. The three regions of extensibility include a first region of extensibility 44 and a second region of extensibility 46 and a third region of extensibility 48. In the embodiment shown in the drawings, the regions of extensibility of the first end region 32 of the sanitary napkin 20 are symmetrical to the respective like regions in the second end region 34, although this may not be the case in other embodiments.

The first region of extensibility 44 of the end region 32 and 34 is preferably located along at least a portion of the longitudinal centerline L of the sanitary napkin. A portion of the first region of extensibility 44 is preferably located adjacent one of the end edges of the main body portion 22. Preferably, the first region of extensibility 44 is a generally pie-shaped region centered with respect to the longitudinal centerline. The first region of extensibility 44 preferably has a peak or apex 50 that runs along the longitudinal centerline L. Preferably, the peak 50 extends substantially the entire way of the end edge 52 of the central region 36. In the embodiments shown in the drawings, the first region of extensibility 44 is also preferably primarily extensible in the transverse direction (as shown by the arrows). This allows the first region to stretch with the wearer's panties, preferably in the region of the wearer's buttocks. The first and second forehead regions 32 and 34 preferably have equal stretchability so that the wearer can wear both ends of the sanitary napkin 20 in the back crotch area of her panties.

The second region of extensibility 46 is preferably disposed laterally outward of at least a portion of the first region of extensibility 44. The second region of extensibility 46 is disposed on one side of the first region of extensibility 44. The second region of extensibility 46 extends toward and preferably in one of the longitudinal side edges 26 of the main body portion 22 of the sanitary napkin 20. As shown in the drawings, if the sanitary napkin 20 is provided with flaps 24, this region of extensibility may even extend beyond the longitudinal side edge 26 of the main body portion into the side flaps 24. In the embodiment shown in the drawings, the area of the second region of extensibility 46 which overlies the main body portion 22 is preferably roughly triangular in shape.

In the embodiment shown in the drawings, the second region of extensibility 46 is extensible in a direction intermediate the longitudinal and transverse directions. Preferably, in this embodiment, the second region of extensibility 46 is extensible in a direction having a primary vector component that forms an angle A, as shown in Figure 1, of between about 45° and about 55°, preferably about 48°, with the longitudinal centerline L. The open portion of the angle A is rotated so that the angle faces the transverse centerline T of the sanitary napkin 20. As long as the angle A is less than 90°, this provides an "inward" extensibility, or an extensibility with a primary vector component directed inwardly, toward the transverse centerline T. This can be contrasted with regions having an "outward" extensibility, which have a primary vector component oriented away from the transverse centerline. An outward extensibility would be present if the extensibility were perpendicular to the arrows shown in region 46. The terms "inwardly oriented" and "outwardly oriented" refer to the direction of extensibility, rather than the direction in which the region may retract, which is also shown by one of the heads on each of the arrows in Figure 1.

The third region of extensibility 48 is preferably disposed laterally outwardly of at least a portion of the first region of extensibility 44 on the other side of the first region of extensibility 44. The third region of extensibility 48 extends toward and preferably to one of the longitudinal side edges 26 of the main body portion 22 of the sanitary napkin 20. The third region of extensibility 48 may also extend into the side flaps 24. The portion of the third region of extensibility 48 that overlies the main body portion 22 is also roughly triangular in shape. In the embodiment shown in the drawings, the third region of extensibility 48 is extensible in a direction intermediate the longitudinal and transverse directions. Preferably, also in this embodiment, the third region of extensibility 48 has an inwardly oriented extensibility in a direction having a primary vector component that forms an angle of between about 45° and about 55°, preferably about 48°, with the longitudinal centerline L. In the preferred embodiment shown in the drawings, the second and third regions of extensibility 46 and 48 are symmetrically disposed on either side of the first region of extensibility 44.

The sanitary napkin 20 differs from many prior art absorbent articles in that it preferably has an overall extensibility that is in diagonal directions. As used herein, "diagonal" generally means from a corner 27 of the main body portion to the corner 27 on the opposite side of the longitudinal and transverse centerlines. This is illustrated in Figure 5. As shown in Figure 5, the primary direction of overall extensibility of the main body portion 22 of the sanitary napkin 20 is preferably oriented in a direction that forms an angle B with the longitudinal centerline L. The angle is greater than 0° and less than 45°, and is preferably between about 15° and about 30°, and for the embodiment shown in the drawings is preferably about 20°.

It is to be understood that the sanitary napkin 20 is preferably extensible in both diagonal directions extending between the four corners of the main body portion 22. Thus, the sanitary napkin 20 not only has a primary component of extensibility oriented at the angle B shown in Fig. 5 (in which the angle is counterclockwise with respect to the longitudinal centerline L rotated clockwise) but also at an equal angle rotated clockwise with respect to the longitudinal centre line L.

The amount of extensibility provided to the sanitary napkin 20 is also important. The sanitary napkin 20 shown in the drawings is preferably capable of longitudinal extensibility along the longitudinal centerline L in the following amounts at the indicated forces: 5% elongation under a force of less than or equal to about 200 grams; 10% elongation under a force of less than or equal to about 550 grams; 15% elongation under a force of less than or equal to about 900 grams; and 25% elongation under a force of less than or equal to about 1600 grams. The sanitary napkin 20 is preferably elastically extensible in the longitudinal direction. The sanitary napkin 20 may have a small amount of set (up to about 10%) after being stretched in the longitudinal direction.

The sanitary napkin 20 shown in the drawings is preferably capable of transverse extensibility in the central region of the main body portion 22, measured along the transverse centerline T, in the following amounts under the specified forces: 5% elongation under a force of less than or equal to about 75 grams; 10% elongation under a force of less than or equal to about 150 grams; 15% elongation under a force of less than or equal to about 250 grams; and 25% elongation under a force of less than or equal to about 400 grams. The sanitary napkin 20 shown in the drawings is preferably capable of transverse extensibility in the end regions 32 and 34 of the main body portion 22, measured parallel to the transverse centerline, in approximately the same amounts and the same forces. The sanitary napkin 20 is preferably elastically stretchable in the transverse direction in the central region 36 and the end regions 32 and 34. The sanitary napkin 20 may have a small amount of set (up to about 10%) after being stretched transversely in these regions.

The sanitary napkin 20 shown in the drawings is preferably capable of diagonal extensibility in the following amounts at the forces indicated: 5% elongation under a force of less than or equal to about 200 grams; 10% elongation under a force of less than or equal to about 500 grams; 15% elongation under a force of less than or equal to about 850 grams; and 15% elongation under a force of less than or equal to about 1500 grams. All forces indicated herein are measured with one inch (2.54 cm) width clamps as described in the Test Methods section below. The sanitary napkin 20 is preferably elastically extensible in the diagonal direction. The sanitary napkin 20 may have a small amount of set (up to about 10%) after being diagonally stretched.

In the case of all of the extensibility directions discussed in the preceding paragraphs, the sanitary napkin 20 is preferably not so highly extensible at low force levels that it is difficult to place in the wearer's undergarments. Preferably, the sanitary napkin 20 is not extensible by an amount greater than or equal to about 10 under forces of less than or equal to about 50 grams in any of the directions for which extensibility was given above. It should be understood, however, that these, like the extensibilities given elsewhere herein, are preferred amounts and the absorbent articles of the present invention are not limited to those having extensibilities in the amounts described herein, unless otherwise stated in the appended claims.

The ability to stretch diagonally is possible because of the direction of extensibility of the various regions of the topsheet 38 and the backsheet 40 and the omnidirectional extensibility of the preferred absorbent core 42 described herein. The total diagonal extensibility provides several advantages to the sanitary napkin 20. The diagonal extensibility helps the sanitary napkin accommodate diagonal stretching of the wearer's panties associated with hiking or similar movements. The total diagonal extensibility reduces tension on the sanitary napkin, which can result in the undesirable tendency of the front edge regions of the sanitary napkin to fold over the rest of the main body region 20 (it prevents "rolling over" of the front edge, a problem which can result in loss of coverage and soiling of the wearer's undergarments). Without wishing to be bound by any particular theory, it is believed that reducing front edge roll over contributes at least in part to the fact that the sanitary napkin 20 is better able to accommodate the aforementioned diagonal stretching. In addition, forming a sanitary napkin with greater extensibility in a diagonal direction than in the longitudinal direction gives the sanitary napkin greater stiffness along the longitudinal centerline (than a sanitary napkin having its greatest extensibility in the longitudinal direction), which also tends to reduce front edge roll over.

The extensibility of the sanitary napkin 20 and the various regions thereof can be provided in any suitable manner. In the embodiment shown in the drawings, the extensibility is provided by forming an extensible network in the desired areas of the topsheet 38 and the backsheet 40 of the sanitary napkin 20. The extensible network is formed by a process which may be referred to herein as forming the base materials of the topsheet and the backsheet into a stretchable elastic-like film (or "SELFing" the base materials of the topsheet and the backsheet). A suitable process for forming an extensible network into the topsheet 38 and the backsheet 40 is described in U.S. Patent 5,518,801 entitled "Web Materials Exhibiting Elastic-Like Behavior" issued to Chappell et al. on May 21, 1996.

As shown in Figure 1, the topsheet 38 and the backsheet 40 preferably have a plurality of extensible network regions formed therein. One extensible network region is formed for the central region 36 of the main body portion 22, and one extensible network region is formed for each of three regions of extensibility formed in the end regions 32 and 34 of the sanitary napkin 20. The different extensible network regions preferably comprise all areas of a single topsheet or backsheet base material having a pattern of regions formed therein. In this embodiment, both the topsheet 38 and the backsheet 40 have identical extensible network regions formed therein (although the extensible network is not shown on the backsheet 40 in FIG. 4 for simplicity of illustrating the adhesive pattern thereon). Preferably, the extensible networks in the topsheet 38 and the backsheet 40 are aligned directly on top of each other.

As shown in Figures 1 and 2, each of the stretchable networks comprises at least two visually distinct regions, first and second network regions 64 and 66. Preferably, each of the stretchable networks comprises a plurality of first and second network regions 64 and 66. In the preferred embodiment shown, the first network regions 64 are substantially planar. The second network regions 66 preferably comprise a plurality of deformations in the form of raised rib-like elements 74.

The properties of the first and second network regions 64 and 66 can also be expressed as the length of the respective regions measured topographically across the surfaces of those regions when the stretchable network is in an unstressed state (or the "surface path length" of the first and second network regions). The second network region 66 has a surface path length that is greater than that of the first network region 64. When elongation forces are applied to the stretchable networks, the rib-like elements 74 undergo a geometric deformation under which they flatten and stretch, while the first regions undergo deformation at the molecular level. This causes the stretchable network regions to exhibit elastic-like behavior in the direction of the arrows when subjected to an applied and subsequently released elongation.

The general properties of stretchable network regions are described in more detail in US Patent 5,518,801, issued to Cappell et al.

The stretchable network(s) may be formed by separately advancing the base materials of the topsheet and backsheet between meshing patterned rollers, by pressing the base material between meshing plates having a pattern formed therein, or by molding. The stretchable network(s) may be formed at various stages in the assembly of the components of the sanitary napkin 20 shown in the drawings. The stretchable network(s) may be formed in the components of the sanitary napkin before they are joined together to form the sanitary napkin. Alternatively, the stretchable network(s) may be formed in the fully assembled sanitary napkin. Preferably, in the embodiment shown in the drawings, the stretchable network(s) are formed in the topsheet 38 and the backsheet 40 before they are joined together to enclose the absorbent core 42 therebetween. The absorbent core 42 may, but need not, have an extensible network formed therein, as it preferably has multi-directional extensibility as described above. Preferably, the absorbent core 42 in the embodiment shown in the drawings does not have an extensible network formed therein.

The portions of the topsheet 38 and backsheet 40 that extend beyond the edges of the absorbent core 42 form a flange 76. These portions of the topsheet 38 and backsheet 40 may be joined in any manner that does not interfere with the ability of the sanitary napkin to stretch. Preferably, in the illustrated embodiment, the topsheet 38 and backsheet 40 are bonded using stretchable adhesives over substantially all of the portions that extend beyond the edges of the absorbent core 42 and using a crimp seal 78 for additional strength at the end edges 28 of the main body portion 22 where the topsheet 38 and the backsheet 40 are densified by the application of pressure or heat and pressure. A suitable stretchable adhesive is Fuller 2352 adhesive available from HB Fuller Company of Badnais Heights, MN. Preferably, a small amount of the adhesive contacts the edges of the absorbent core 42 to hold the absorbent core 42 in place.

The crimp seal 78 should not interfere with the ability of the components of the sanitary napkin to stretch. Preferably, the stretchable regions of the sanitary napkin connected by the crimp seal 78 are capable of stretching by the amounts and under the forces specified above for the sanitary napkin 20 (see, e.g., the transverse stretchability in the end regions). (The crimp seal 78, however, is capable of allowing the components to stretch in multiple directions.) The crimp seal 78 may thus be referred to as an stretchable crimp seal (although the crimp seal 78 does not provide inherent stretchability when not used with stretchable components). The crimp seal 78 preferably comprises a liquid impermeable seal. The crimp seal 78 preferably includes a sinusoidal seal line along which portions of at least one of the topsheet 38 or the backsheet 40 are compressed and/or welded together. The crimp seal 78 shown in Figure 1 is in a sinusoidal pattern that is preferably arranged in a substantially curved configuration. Other configurations, such as straight sinusoidal patterns, may also be used. Without wishing to be bound by any particular theory, it is believed that the crimp seal 78 allows the area of the sanitary napkin adjacent thereto to stretch because the curves of the sinusoidal configuration provide the crimp seal 78 with a "slack" that can be stretched until it at least partially straightens.

Numerous variations of the expandable crimp seal 78 are possible. For example, the crimp seal can be wrapped around all or a portion of the perimeter of the sanitary napkin, including the distal edges of the flaps (described below) In addition to the sinusoidal patterns, other suitable patterns that provide the desired "looseness" including, but not limited to, zigzag patterns may also be used. The stretchable crimp seal 78 may have a sinusoidal (or other) pattern that varies in bandwidth, amplitude and frequency. In addition, multiple sinusoidal waves (or waves of other configurations) may be aligned in phase adjacent to one another. Such multiple crimp seals may be used to ensure that a continuous crimp is present around the desired region of the perimeter of the sanitary napkin after processing. For example, it is possible to cut through a crimp seal during manufacture. This would most commonly occur when a web of sanitary napkins is cut at the end edges into individual sanitary napkins by the final cutting operation (or "final knife"). Multiple crimp seals ensure that liquids are not drawn through the crimp seal 78 even if a region of the crimp seal is cut during manufacture.

In other embodiments, the continuous sinusoidal crimp seal can be combined with discontinuous (or intermittent) bonding patterns. The discontinuous bonding patterns can be in the form of discontinuous sinusoids or other suitable discontinuous patterns. The discontinuous patterns should be in configurations such that if any portion of the crimp seal is cut during manufacture, the discontinuous pattern creates a tortuous flow path to capture fluids that may attempt to be drawn through the crimp seal. These patterns can also provide increased manufacturing flexibility since the location where the cutting assembly of the final blade falls on the crimp joint is not critical.

The expandable crimp seal 78 provides a number of advantages. These include, but are not limited to, the following. The expandable crimp seal 78 forms of course, an impermeable barrier to liquids attempting to leak from the ends 78 of the sanitary napkin 20. It also allows the components of the sanitary napkin to stretch, even though it is continuous. It was previously believed that a discontinuous bonding pattern should be used to avoid interfering with the ability of the components of a stretchable absorbent article to stretch. Thus, the stretchable crimp seal 78 helps prevent the undesirable tendency of the end edge regions of the sanitary napkin to fold over the remainder of the main body region. Without wishing to be bound by any particular theory, it is believed that this occurs because the stretchable crimp seal 78 eliminates any existing differences in stretchability between the flange 76 and the remainder of the main body region 22 that would cause the flange 76 to curl when the main body region 22 is stretched.

The sanitary napkin 20 shown in Figures 1-4 also includes a pair of flaps 24 connected to the main body portion 22. The flaps 24 extend laterally outwardly beyond the elongated side edges 26 of the main body portion 22 from their proximal edges 24A to their distal edges (or "free ends") 24B. The flaps 24 extend outwardly from at least the central region 36 of the main body portion 22. As shown in Figure 1, each flap 24 is divided into a front half 54 and a back half 56 by a transverse flap centerline T1. The transverse flap centerline T1 may coincide with the main transverse centerline T of the sanitary napkin, but this is not absolutely necessary. The flaps 24 are each connected to (or associated with) the main body portion 22 along a junction. This is typically a longitudinally oriented (or "longitudinal") junction, such as transition lines 68. As used herein, the terms "junction" (or "transition line") refer to regions in which the flaps 24 extend from or are connected to the main body portion 22.

The flaps 24 may be connected to the main body portion 22 in any suitable manner. The term "connected" as used herein includes configurations in which one element is directly secured to another element by attaching the element directly to the other element; configurations in which the element is indirectly secured to the other element by attaching the element to one or more intermediate elements which in turn are attached to the other element; and configurations in which one element is integrally formed with another element, that is, one element is an integral part of the other element. Preferably, in the embodiment shown in Figures 1-4, the flaps 24 are integrally formed with the main body portion 22 (that is, the flaps 24 comprise integral extensions of the topsheet 38 and the backsheet 40).

The extensions of the topsheet 38 and the backsheet 40 having the flaps 24 may be bonded together in any suitable manner. For example, the extensions of the topsheet 38 and the backsheet 40 forming the flaps may be bonded together by adhesive over their entire surface or any suitable region thereof to form the flaps 24. Preferably, the extensions of the topsheet 38 and the backsheet 40 having the flaps 24 (such as those regions forming the flange 76) are bonded together over their entire interface with a continuous layer of a stretchable adhesive, such as Fuller 2352 adhesive.

The flaps 24 may be in any suitable configuration. Suitable flaps are described in Reexamined Patent No. B1 4,589,876, entitled "Sanitary Napkin," issued to Van Tilburg, Certificate of Reexamination issued April 27, 1993; U.S. Patent 4,687,478, entitled "Shaped Sanitary Napkin With Flaps," issued to Van Tilburg on August 18, 1987; U.S. Patent 5,389,094, entitled "Absorbent Article Having Flaps and Zone of Differential Extensibility," issued to Lavash et al. on February 14, 1995 and in International Patent Application, Official Serial No. PCT/US96/15957, entitled "Absorbent Article Having Flaps With Step Configuration and Zones of Extensibility", filed October 3, 1996 in the name of Lash et al.

In a preferred embodiment, the sanitary napkin 20 has several improved features for reducing stresses on the main body region 22 and on the flaps 24 when the flaps 24 are placed around the side edges of a wearer's undergarments.

One improved feature described above is that the central region 36 of the main body portion 22 is provided with lateral extensibility. This allows the central region 36 to expand to assist the flaps 24 in folding around the curved side edges of the wearer's undergarment. As shown here in Figure 1, the transverse extensibility preferably extends from the central region 36 of the main body portion 22 across the longitudinal side edges 26 of the main body portion 22 into the flaps 24. In the embodiment shown, this lateral extensible region preferably terminates at a region 70 surrounding the flap adhesive 82. The region surrounding the flap adhesive 70 is preferably stiffer than the rest of the flap 24 to assist in manipulating the flaps 24 as the consumer uses them. A further improved feature is that in the embodiment shown, although the side flaps 24 are integrally formed with the main body portion 22, they are provided with zones of extensibility 72 which originate at a point which is inboard of the longitudinal side edge 42A of the absorbent core 42 of the sanitary napkin 20 (i.e., in the second and third regions of extensibility 46 and 48). It is desirable to have zones of extensibility 72 which are inboard of the longitudinal side edges 42A of the absorbent core 42 for several reasons. First, by initiating extensibility inboard of the longitudinal edges 42A of the absorbent core 42, the total amount of extensibility which can be provided to flaps 24 can be significantly increased with respect to flaps which have their total extensibility laterally outside of the absorbent core 42. Second, the extensibility can more effectively accommodate a wider variety of panty sizes and styles when it is located inside the longitudinal edges 42A of the absorbent core 42. The difficulty in providing the sanitary napkin with integral flaps having extensibility that is inside the edges of the absorbent core has been that the absorbent core has typically been both inextensible and too thick to form extensible network regions therein. In the embodiment shown in the drawings, however, these difficulties are overcome by using an extensible absorbent core 42 surrounded by a topsheet 38 and a backsheet 40, both having the desired extensible regions formed therein, and by bonding the topsheet 38 and the backsheet 40 together.

The extensible regions of the topsheet and backsheet are vertically aligned with the extensible network regions in the topsheet 38 and directly overlie those in the backsheet 40. The extensible regions of the topsheet 38 and backsheet 40 may be bonded to the absorbent core 42 and extend with the absorbent core. Alternatively, either or both of the topsheet 38 and backsheet 40 may be unattached to the absorbent core 42 in these regions. Preferably, at least the backsheet 40 is loosely attached to the absorbent core 42 in these regions.

Yet another improved feature of the sanitary napkin 20 in the embodiment shown in the drawings is the direction of the primary vector component of extensibility in the corner regions 86 of the flaps 24 and the adjacent regions of the main body portion 22 (the second and third regions of extensibility 46 and 48). The corner regions 86 of the flaps occur where the outer edges of the flaps 24 intersect the longitudinal side edges 26 of the main body portion 22 when the sanitary napkin 20 is shown in plan view. The corner regions 86 include not only these corners, but also surrounding regions and adjacent regions inboard of the edges of the flaps 24. It is nor is it necessary that there be a sharp angle formed at the intersection of these edges or demarcation lines to designate the same. A more detailed description of the corner regions for a sanitary napkin with flaps is contained in U.S. Patent 5,389,094 issued to Lavash et al. The corner regions 86 of the embodiment shown in Fig. 1 are located in the same region as the zones of extensibility 72.

The direction of the primary vector component of extensibility in the corner regions 86 in various embodiments may be primarily in the transverse direction, primarily in the longitudinal direction, or in a direction intermediate the transverse or longitudinal direction. In the preferred embodiment shown in the drawings, the direction of the primary vector component of extensibility in the corner regions 86 is preferably in the same direction as that of the adjacent region of extensibility of the main body portion 22. The adjacent region of extensibility is either the second or third region of extensibility 46 and 48. Since these two regions of extensibility are preferably symmetrical, the relative direction of this primary vector component is generally the same for both corner regions 86 of each flap 24. The term "relative direction" refers to the angle that the primary vector component makes with the longitudinal L. The relative direction of the primary vector component of extensibility of the corner regions 86 thus extends at an angle A which is directed inwardly toward the transverse centerline T of the sanitary napkin 20.

The inward orientation of the primary vector component of extensibility in the corner regions 86 provides several advantages. The extensibility is designed to more effectively reduce the stresses on the flaps 24 when folded around the curved side edges of the wearer's undergarment than in a number of previous attempts to solve this problem. In particular, the extensibility is intended to solve problems caused by the forces acting on both the main body portion 22 of the sanitary napkin 20 and the flaps 24 are effective when the flaps 24 are placed around the curved side edges of the crotch region of the wearer's underwear.

One such problem that the orientation of stretchability described here is intended to solve is referred to herein as "wing slippage" or flap slippage. This involves the flap adhesive 82 (described in more detail below) which is designed to secure the flaps 24 around the undergarment by attaching the flaps 24 to the bottom of the wearer's undergarment or to the opposite flap. Folding the flaps 24 around the side edges of the wearer's undergarment causes tension to be applied to the flaps. This tension can cause the flap adhesive 82 to become unbound with the bottom of the wearer's undergarment or to the opposite flap, causing it to come loose or "slip off" therefrom. One way to attempt to eliminate wing slippage is to increase the strength of the flap adhesive 82. Increasing the strength of the flap adhesive 82, however, can lead to other problems.

Another problem that the orientation of the stretchability described here is intended to solve arises from the fact that the tension created by folding the flaps 24 around the side edges of the wearer's undergarments can also exert a tension on the main body portion 22 of the sanitary napkin 20. This is particularly important to consider with highly flexible sanitary napkins such as the stretchable sanitary napkin described here. The tension exerted on the main body portion 22 by folding the flaps 24 causes the end regions 32 and 34 of the main body portion 22 to separate from the adhesive attachment to the wearer's undergarments. This results in the end edges 28 of the main body portion 22 folding over or rolling over onto the top of other regions of the main body portion 22.

Yet another problem seen in highly flexible sanitary napkins, which is caused by the tension caused by folding the flaps 24 is shown in Fig. 6. Fig. 6 shows a highly flexible sanitary napkin 20. Although it is to be understood that the sanitary napkin 20 has flaps, it is shown in Fig. 6 without flaps for simplicity since the effect of the forces on the main body portion 22 is primarily of interest. As shown in Fig. 6, the tension created by folding the flaps 24 can pull one or both of the ends of the main body portion 22 inwardly toward the transverse centerline and cause portions of the main body portion 22 to fold over one another. The panty-attached adhesive on the garment-facing side 20B of the sanitary napkin can cause the folded over portions to adhere to the underlying portions of the main body portion 22. This may be referred to herein as a "Z-fold" in reference to the shape assumed by the main body portion.

The direction of the primary vector component of extensibility in the corner regions 86 substantially reduces or eliminates these problems. It has been found that most of these problems are due to the tension forces exerted between the end regions of the main body portion 22 and the regions of the flaps 24 secured by the flap adhesives 82. The direction of the primary vector component of extensibility in the corner regions 86 is preferably a direction substantially parallel to the line of tension between these regions of the sanitary napkin. This extensibility reduces the tension between the end regions of the main body portion 22 and the regions of the flaps 24 secured by the flap adhesives 82. In addition, the direction of extensibility of the corner regions 86, like that of the second and third regions of extensibility, is also directed inwardly toward the transverse flap centerline T1. Some previous efforts have been directed at orienting the stretchable areas of the flaps in the same direction as the stretchability of the wearer's panty elastics. This stretchability provided to the sanitary napkin described here is in a direction which crosses that of the wearer's panty elastics and is more or less perpendicular to them.

It should also be noted that in the preferred embodiment shown in the drawings, the corner regions 86 and the second and third regions of extensibility 46 and 48 are preferably elastically extensible due to the formation of the extensible network regions therein. This is accomplished without attaching conventional elastic bands to the material having these regions of the sanitary napkin. Furthermore, the less extensible bands (first network regions) do not place tension on this region of the sanitary napkin such that the flaps fold under the absorbent core.

The corner regions 86 of the flaps of the sanitary napkin 20 shown in the drawings, together with the adjacent second and third regions of extensibility 46 and 48, are preferably capable of extensibility in a direction parallel to the first network regions 64 therein by the following amounts at the forces indicated: 5% elongation under a force of less than or equal to about 75 grams; 10% elongation under a force of less than or equal to about 150 grams; 15% elongation under a force of less than or equal to about 175 grams; and 25% elongation under a force of less than or equal to about 250 grams. The corner regions 86 of the flaps 24 and the adjacent second and third regions of extensibility 46 and 48 in the embodiment shown are preferably elastically extensible. The corner regions 86 of the flaps 24 and the adjacent second and third regions of extensibility 46 and 48 shown in the drawings all have a small amount of settlement (up to about 10%) after being stretched.

Numerous alternative embodiments of the flaps 24 shown in the drawings are possible. In (less preferred) embodiments, the corner regions of the flaps 24 could have regions that are stretchable in the transverse direction as a whole, in the longitudinal direction as a whole, or outwardly in a direction between the longitudinal and transverse directions, rather than having an inward stretchability described here. Furthermore, it is also possible in less preferred embodiments to combine the less stretchable bands with the first regions 64 of the stretchable network at the corner regions 86 of the flaps. The less stretchable bands may also be omitted from the other regions of the sanitary napkin, including the main body region 22.

The garment facing surface 20B of the sanitary napkin 20 may include, and preferably includes, fasteners for attaching the sanitary napkin to the wearer's undergarments. Figure 1 shows the central pad fastener 80 which is designed to secure the main body portion 22 of the sanitary napkin to the crotch region of an undergarment. Any type of fastener known in the art, such as adhesive fasteners, mechanical fasteners, may be used as the central pad fastener 80. Fasteners with adhesives have been found to work well for this purpose, with pressure sensitive adhesives being preferred.

The central pad fastener 80 may have any suitable configuration. Preferably, as shown in Figure 4, the central pad fastener 80 has a configuration comprising a longitudinally oriented zone of adhesive 80A having a plurality of "branches" 80B, 80C and 80D extending therefrom. The branches 80B, 80C and 80D lie in the end regions 32 and 34 of the main body portion 22 and preferably extend from the longitudinal centerline L toward the perimeter 30 of the main body portion 22. In each end region, one of the adhesive branches 80B, 80C and 80D extends into each of the three regions of extensibility 44, 46 and 48. Preferably, the adhesive branches 80B, 80C and 80D are oriented in a direction substantially perpendicular to the primary direction of extensibility of the respective regions. This has been found to allow stretch in the desired directions while at the same time firmly securing the sanitary napkin 20 in place within the wearer's undergarments. The adhesive may be applied to the backsheet 40 in any suitable manner. Preferably, in the embodiment shown, the adhesive having the various zones and adhesive branches is a stretchable, hot melt adhesive such as Fuller 2238 adhesive available from The HB Fuller Company, which is applied in a spiral pattern to impart a degree of stretch.

The outer surface of the flaps 24 adjacent the distal edges 24B of the flaps is preferably provided with a flap fastener, such as the flap fastener 82. The flap fastener 82 is used to help hold the flaps 24 in position after they have been placed around the edge of the crotch region of the panty. Although the flap fastener 82 can be any suitable size, it is preferably between about 60% and about 80% of the length of the distal region 24B of the flaps 24. Suitable adhesive fasteners are described in more detail in U.S. Patent 4,917,697. The flaps 24 can be held in position by attaching the flaps 24 to the undergarment or to the opposing flap.

The fasteners, the central pad fastener 80 and the flap fasteners 82, used in the present invention are not limited to adhesive attachment means. Any type of fastener used in the art may be used for such a purpose. For example, the sanitary napkin 20 could be secured to the wearer's undergarments by mechanical fasteners such as VELCRO hook material or by the fasteners described in U.S. Patent 4,946,527, entitled "Pressure-Sensitive Adhesive Fastener and Method of Making the Same," issued to Battrell on August 7, 1990 or U.S. Patent 5,392,498, entitled "Non-Abrasive Skin Friendly Mechanical Fastening System," issued to Goulait et al. on February 28, 1995. However, for simplicity, fasteners are described in terms of adhesive attachment means.

The adhesive attachment means are each covered with removable release strips, a central pad release strip and a flap release strip, both designated 84. The pressure sensitive adhesives should be covered with release strips 84 to protect the adhesives from sticking to foreign surfaces prior to use. Suitable release strips are described in U.S. Patent 4,917,697. In a preferred embodiment, the flaps 24 are folded over the topsheet and the flap adhesives 82 are covered by a single release paper. The adhesive attachment means on such flaps, rather than being covered by a release strip, could be releasably adhered to a release surface provided on any other region of the sanitary napkin, including the main body region or flaps, or a separate component attached to the main body region or flaps. For example, the flaps 24 could be folded and stapled as described in U.S. Patent 5,281,209 issued to Osborn et al. on January 25, 1994. The sanitary napkin 20 may also be provided with a particularly preferred release strip which also serves as an individual package for enveloping the sanitary napkin, as described in U.S. Patent 4,556,146 issued to Swanson et al.

The sanitary napkin 20 is used by removing the release tabs 84 and placing the sanitary napkin 20 in a panty. The main body portion 22 is positioned in the crotch region of the panty such that one end of the main body portion 22 extends toward the front portion of the panty and the other end extends toward the rear portion of the panty. The backsheet 40 is positioned in contact with the inner surface of the center of the crotch region of the panty. The center pad adhesive fastener 80 holds the main body portion 22 in position. The flaps 24 are then folded around the side edges of the panty. The flap adhesives 82 secure the flaps 24 to the bottom of the panty or to the opposite flap.

Other embodiments of the absorbent articles described herein are also possible. For example, Figures 7 and 8 show an embodiment of an absorbent article in the form of a composite sanitary napkin 729. The composite sanitary napkin 720 includes a primary absorbent component (or "core tube") 790 which is bonded to the body-facing side of a secondary absorbent component (or "base pad") 792. The primary absorbent component 790 is preferably intended to absorb the surge of bodily fluids discharged by the user. The base pad 792 functions primarily to protect the user's garments from soiling by absorbed fluids which may be expressed from the primary absorbent component 97 or which undesirably bypass into the primary absorbent component 790.

In the embodiment shown in Figures 7 and 8, the primary absorbent component 790 comprises an absorbent structure, such as an absorbent core 794, and an outer cover 796 which envelops the absorbent core 794. The outer cover 796 may comprise any of the materials described above as suitable for the topsheet of the embodiment shown in Figures 1-4.

The absorbent core 794 may comprise any material suitable for absorbing or retaining liquids (e.g., menstrual fluids and/or urine). Examples of suitable absorbent materials include ground wood pulp, commonly referred to as airfelt; creped cellulose wadding; meltblown polymers, including coform; chemically stiffened, modified, or crosslinked cellulosic fibers; synthetic fibers, such as crimped polyester fibers; peat moss; tissue, including tissue wrappers and tissue laminates; absorbent foams; absorbent sponges, superabsorbent polymers; absorbent gelling materials; or any equivalent material or combinations of materials or blends thereof. The configuration and construction of the absorbent core can also be varied (e.g., the absorbent core can have varying thickness zones (e.g., profiled so as to be thicker in the center), have hydrophilic gradients, superabsorbent gradients, or acquisition zones of lower density and lower average basis weight; or can have one or more layers or structures).

The primary absorbent component 790 may further include an optional acquisition layer 798, as shown in Figure 9. The acquisition layer 798 may be a separate component positioned between the outer cover 796 and the absorbent core 794, or it may be an integral part of a composite outer cover. The acquisition layer 798 may serve several functions, including enhancing the wicking of exudates over and into the absorbent core 794 and/or containing absorbent material within the absorbent core 794.

The base pad 792 of the composite sanitary napkin 720, as shown in Figures 7 and 8, preferably comprises the sanitary napkin 20 shown in Figures 1-4. The elements of the base pad 792 shown in Figures 7 and 8 discussed above in connection with Figures 1-4 are designated by the number 700 before the same reference numerals used in Figures 1-4. The primary absorbent component 790 may or may not be stretchable. As shown in Figure 7, in a preferred embodiment, the outer cover 796 of the primary absorbent component 790 comprises the same material used for the topsheet 738 of the base pad. Preferably, after the outer cover 796 has been wrapped around the primary absorbent component 790, the regions of extensibility in the outer cover 796 are aligned directly over those of the topsheet 738 on the base pad 792, as shown in Figure 7.

The compound sanitary napkins (without the stretchability described here) are further described in US Patent 4,425,130, issued to DesMarais on January 10, 1984 and in Statutory Invention Registration H1614, entitled "Body Fitting Compound Sanitary Napkin", issued in the name of Mayer et al. on November 5, 1996.

In alternative embodiments, the components such as the topsheet and backsheet of the absorbent articles described herein may optionally be replaced with suitable (stretchable) components described in the patents and patent applications incorporated by reference herein. For example, in a non-limiting example, the backsheet having the stretchable network regions described herein could be replaced with a liquid-impermeable, stretchable adhesive film if desired. In addition, the absorbent articles described herein may optionally be provided with any of the properties and/or features described in the patents and patent applications incorporated by reference herein.

For example, other embodiments of the sanitary napkin 20 may be stretchable under the forces associated with wearing the sanitary napkin in a panty in the various directions described herein in amounts described in U.S. Patent 5,611,790. The sanitary napkin of the present invention may also be provided with any of the other features of the sanitary napkins described in U.S. Patent 5,611,790, including a structure that provides a "force wall" to prevent elongation beyond a certain amount without significant increases in the amount of force exerted on the sanitary napkin.

In these or other embodiments, the absorbent articles described herein may be provided with zones of extensibility in any other suitable configurations or with stretch in any other suitable directions. The absorbent articles described herein may also be provided with different regions that extend more or less than other regions for improved contact with the wearer's body or for other purposes. Some examples of absorbent articles with such regions are described in the patents and patent applications incorporated herein by reference. For example, sanitary napkins with Regions of different extensibility are described in U.S. Patent 5,611,790 issued to Osbon et al. Sanitary napkins with improved mechanisms for maintaining the sanitary napkin in contact with the wearer's body are described in PCT Publication No. WO 95/20931, published August 10, 1995, filed in the name of Osborn et al. on February 2, 1995.

The absorbent articles described herein may also be provided with regions that are stiffer or more flexible than other regions for improved contact or other purposes. For example, Fig. 4 shows that the sanitary napkin 20 may be provided with optional stiffeners 90. The optional stiffeners 90 are preferably provided along at least a portion of the periphery of the absorbent core 42, particularly along the longitudinal side edges 42A of the absorbent core 42. The optional stiffeners may be positioned inside the entire periphery of the absorbent core 42. Preferably, however, the optional stiffeners 90 are not present along the longitudinal centerline L of the sanitary napkin 20, as shown in Fig. 4.

In the embodiment shown in Figure 4, the optional stiffeners 90 comprise a 60% polyester/40% rayon material available from fabric stores known as PELLON® Kraft binder material sold by Freudenbert Nonwovens. The PELLON stiffening material preferably has a thickness of 0.35 mm, a bending resistance of about 33 grams, and a Taber stiffness of about 0.85 g/cm. The PELLON stiffening material may be positioned between layers of the sanitary napkin 20. The PELLON stiffening material is preferably positioned beneath the absorbent core 42 and bonded to the bottom of the absorbent core by adhesive, such as a Fuller 2031 adhesive.

The optional stiffeners 90 shown in Fig. 4 provide the longitudinal side edges of the absorbent core and the end regions 32 and 34 of the sanitary napkin 20 with an additional degree of stiffness to reduce undesirable bunching and to eliminate the problem of "rolling over" of the front edge discussed above. to reduce or eliminate. The optional stiffeners 90 also provide the zone of the sanitary napkin which lies along the longitudinal centerline thereof with increased "lift" for improved contact with the wearer's body. Without wishing to be bound by any particular theory, it is believed that the increased lift may contribute to the fact that, due to the presence of the stiffeners 90, all of the lift is concentrated in the region along the longitudinal centerline between the inside edges of the stiffeners 90. The stiffening surfaces on the outer periphery or sides of the sanitary napkin may also help to secure the sanitary napkin to the wearer's panties.

However, it has been recognized that if a non-stretch material such as PELLON is used for stiffness, the extensibility of the stiffened region of the sanitary napkin 20 is reduced or eliminated. However, this embodiment of the sanitary napkin 20 can still function effectively, particularly if a gap is left between the stiffener 90 along the longitudinal centerline L. Such an embodiment is still capable of stretching along the longitudinal centerline and in the diagonal direction as stated above. The embodiment also allows the first region of stretchability 44 in the end regions 32 and 34 to stretch in the transverse direction. If it is not desired to affect the extensibility of the sanitary napkin, a stiffened material having a degree of extensibility can be chosen.

Moreover, in alternative embodiments, instead of being provided with flaps, the absorbent article could be provided with undergarment covering components or ("side wrap elements") which preferably have a smaller span than conventionally sized flaps and which do not need to be manipulated by the wearer when placed in the wearer's undergarments. Absorbent articles having side wrap elements are described in U.S. Patent 5,584,829, entitled "Absorbent Articles Having Panty Covering Components That Naturally Wrap the Sides of Panties", issued to Lavash et al. on December 17, 1996; U.S. Patent Application Serial No. 08/124,180, entitled "Absorbent Articles Having Panty Covering Components Comprising Extensible Web Materials Which Exhibit Elastic-Like Behavior," filed September 17, 1993 in the name of Mansfield et al. (PCT Publication No. WO 95/07675, published March 23, 1995); and U.S. Patent 5,558,663, entitled "Absorbent Articles Having Undergarment Covering Components With Zones of Extensibility," issued to Weinberger et al. on September 24, 1996.

It should also be understood that all limits and ranges specified herein include all narrower ranges, limits and amounts that are within the specified limits and ranges, and that such narrower ranges and limits may be claimed even though such limits and ranges are not separately listed.

TEST PROCEDURE

Unless otherwise stated, all of the following tests were performed on specimens that were conditioned by being kept in a room at 50% relative humidity and at 73ºF (23ºC) for a period of two hours prior to testing. Tests should be performed under similar conditions.

Capacity of the absorbent material

The absorption capacity of the absorbent material can be determined as follows.

A rectangular sample measuring 2 1/2 inches by 3 inches (6.4 cm by 7.6 cm) of the absorbent material is obtained. The sample is weighed to the nearest 0.1 gram. The sample is then immersed in distilled water for by dipping it into a dish filled with distilled water, such that the sample is not bent or otherwise twisted or folded. The sample is immersed for 20 minutes. The sample is removed from the distilled water and suspended for two minutes to allow the distilled water to drain from the sample. The sample is then weighed to the nearest 0.1 gram and the dry weight of the sample is subtracted. The difference in grams is the absorbent capacity of the sample. The absorbent capacity can then be expressed as a ratio of the absorbent capacity to the dry weight of the sample in grams/gram.

Stretchability tests

The following extensibility tests of the absorbent material or sanitary napkin (or other absorbent article) utilize a constant rate elongation tensile tester such as an Instron Model #1122 Tensile Tester or an EME Tensile Tester, Model No. 559A, available from EME, Inc. P.O. Box 187, Newbury, OH 44065.

The test device is preferably provided with a computer which provides an LCD display for the distance at which the ends of the clamps are from a reference starting position and for the forces on the sample when the clamps are arranged at different distances from the starting position.

The samples are carefully handled to avoid stretching them before the tests are carried out. If the tests are carried out on absorbent articles, the tests should be repeated on samples from five separate products of the same type. If any of the samples falls within the claimed range or limit, the product is considered to fall within the scope of the appended claims.

A. Absorbent Material Stretchability - One inch (2.5 cm) Strip Test Samples for measuring extensibility

The samples are preferably taken from a sheet of absorbent material before it is incorporated into the absorbent article. If this is not possible, the samples of absorbent material can be obtained by carefully removing the absorbent material from the absorbent article. This can be done by peeling off other areas of the absorbent article while being careful not to damage the absorbent article or do anything else that could affect the extensibility of the same.

Samples are obtained by cutting a 1.0 inch (2.54 cm) wide strip of the absorbent material using a JDC Precision Sample Cutter, Model #1-12, available from Thwing-Albert, Philadelphia, PA. The term "absorbent material" as used herein refers to a material that is used essentially as the primary absorbent component of the product, such as the absorbent core of the product. It also includes absorbent materials that have a wicking or storage function.

The strip used as the sample for measuring longitudinal extensibility should be taken from a region of the absorbent article centered on the longitudinal centerline of the absorbent article. The length of the strip should extend the entire length of the region of the absorbent article from which the sample is taken.

If the sample can be taken from a web of absorbent material before the absorbent material is incorporated into the absorbent article, a 1" x 4" strip of fabric should be cut so that its extensibility is in the same direction as it would be oriented in the assembled absorbent article. A sample for measuring longitudinal extensibility should cut from a first sample of absorbent material. The sample for measuring transverse extensibility should be cut from a second sample of absorbent material of the same type as the first (i.e., an identical material or product). Similarly, the sample for measuring diagonal extensibility should be cut from a third sample of absorbent material or absorbent article of the same type as the first (i.e., an identical material or product).

The strip used as the sample for measuring transverse extensibility is a 1.0 inch wide strip cut from the absorbent material that runs parallel to the transverse centerline of the absorbent article (or will be positioned in the composite absorbent article to do so). The strip used as the sample for measuring transverse extensibility can be cut through any one inch wide section of the absorbent material that runs parallel to the transverse centerline. The sample does not have to run along the transverse centerline.

The strip used as a sample for measuring diagonal extensibility is cut through a 1 inch wide section of the absorbent material that will be (or will be positioned to be) at a 45 degree angle to the longitudinal centerline of the absorbent article.

method

Place the specimen loosely on a table. Measure the length of the specimen (the dimension of the specimen that is perpendicular to the one-inch width dimension) to the nearest 0.1 inch (0.25 cm).

Clamp each end of the specimen into the tensile tester using 1-inch (2.54 cm) wide clamps. The clamps of the tensile tester are adjusted so that they can be pulled away from each other in opposite directions (i.e., they can be pulled at a 180-degree angle). The specimen should be centered in the clamps and the clamping pressure should be sufficient to prevent slippage of the specimen in the clamps (this applies to all tensile testing procedures). The specimen should be clamped so that the outermost edge (i.e., the free end) of the clamps is approximately 0.5 inch (about 1.3 cm) inside the end edges of the absorbent material.

Set the gauge length of the tensile tester to the length of the absorbent material (as measured above) less the amount of absorbent material clamped in each of the clamps (typically 1 inch). A gauge length of 2 inches (5 cm) has been found to be suitable. Initiate elongation with a crosshead speed of 20 inches/minute (51 cm/minute). When the sample reaches the gauge length, tare the test fixture load cell to zero. Set the trigger point to collect data at 5 grams of force.

The force and elongation measurements are taken at the desired times and the test is terminated. The force, for the purposes of the appended claims, is the actual force read on the test device when the above procedure is followed. The results are expressed in grams/inch or grams/cm.

If the strips of one inch of absorbent material are extensible in the amounts and under the forces specified in the claims in the following three directions: the longitudinal direction, along a cross-section in the transverse direction, and in the 45º diagonal direction, the absorbent article is considered to be omnidirectionally extensible.

B. Methods for measuring the extensibility of an absorbent article or different regions thereof

This test is used to measure the extensibility of the absorbent article or different regions thereof. The type of test procedure used for this purpose is known as a "grip test". It involves clamping regions of the absorbent article into the clamps of the tensile tester and exerting a tensile force on either the entire absorbent article or the desired regions thereof.

The sample used for testing is the entire absorbent article. Separate samples of the absorbent article of the same type (i.e., identical products) should be used to measure the different directions of extensibility of the absorbent article or extensibility of the different regions of the same.

The absorbent article may be tested for: the longitudinal extensibility of the absorbent article; the transverse extensibility of the absorbent article (both along the transverse centerline and in the end regions of the absorbent article); the diagonal extensibility of the absorbent article; the extensibility in the corner regions of the flaps and those regions of extensibility of the main body region adjacent to the flaps; and the extensibility of the crimp seal.

In this test, one inch (2.54 cm) wide staples are used in the test device. If the absorbent article has regions with different directions of stretch and it is desired to measure the stretch of the different regions, then care should be taken to place both of the staples overall within the desired region. If this is not possible, the staples should be placed as close as possible overall within the desired region.

When testing the longitudinal extensibility of the absorbent article, the clips should be centered about the longitudinal centerline of the absorbent article. When testing the transverse extensibility of the central region of the absorbent article, the clips and the transverse centerline should be centered. When testing for the transverse extensibility of the end regions of the absorbent article, the clips should be located in the end regions so that elongation occurs parallel to the transverse centerline. When testing the diagonal extensibility of the absorbent article, the clips are located in opposite corners of the main body region of the absorbent article so that the primary vector component of the elongation forces pass through the intersection of the longitudinal and transverse centerlines of the absorbent article.

When testing the extensibility between the corner regions of the flaps and the adjacent regions of extensibility of the main body portion of the absorbent article, the clamps should be aligned at the applicable angle A. One clamp is placed in the flap and the other clamp is placed in the region of extensibility of the main body portion. When testing the extensibility of the crimp seal, the clamps are placed centered around the crimp seal so that the elongation is applied in the direction of extensibility of the region containing the crimp seal.

The absorbent article should be clamped so that the outermost edge (i.e., the free end) of the clamps are approximately 0.5 inch (about 1.3 cm) inside the front edges of the absorbent material in the various regions. However, if no absorbent material is present in any part of the region (such as if one clamp is in the corner region of the flaps, or if both clamps are in the region of the crimp seal), clamping inside the edges of the absorbent material is not necessary.

Set the gauge length of the tensile tester to the length of the absorbent material, minus the amount of absorbent material clamped in each of the clamps. Initiate elongation with a crosshead speed of 20 inches/minute (51 cm/minute). When the sample reaches the gauge length, tare the tester's load cell to zero.

The force and extensibility measurements are taken at the desired times and the test is terminated. The results are expressed in grams.

Although particular embodiments of the present invention have been shown and described, it will be apparent to those skilled in the art that various other changes and modifications may be made.

Claims (8)

1. An omnidirectionally extensible absorbent core (40) for a disposable absorbent article (20), wherein the absorbent core (40) is capable of elongation in all directions of up to at least 25% under forces of less than or equal to 80 grams/cm, and wherein the absorbent core (40) comprises a multidirectional extensible nonwoven web, the web having been transversely consolidated in a first direction and compressively treated longitudinally in a second direction, i.e., perpendicular to the first direction. 2. The omnidirectionally stretchable absorbent core (40) of claim 1, which comprises a knitted material. 3. The omnidirectionally extensible absorbent core (40) of claim 1, wherein the multidirectionally extensible nonwoven web comprises a blend of polymeric fibers of fibrous superabsorbent hydrogel-forming material. 4. Multidirectionally stretchable absorbent article (20) for wearing in an undergarment, the absorbent article (20) being characterized in that it comprises: a multidirectionally stretchable, liquid-permeable top layer (38) a multidirectionally stretchable, liquid-impermeable backsheet (40) which is at least partially peripherally bonded to the topsheet (38); and an omnidirectionally extensible absorbent core (42) according to claim 1 positioned between the topsheet (38) and the backsheet (40). 5. The extensible absorbent article (40) of claim 4, wherein the topsheet (38), the backsheet (40) and the absorbent core (40) comprise a main body portion (22) having at least two regions extensible in different directions, at least one region capable of elongation of 25% under forces of less than or equal to 500 grams. 6. The multidirectionally stretchable absorbent article (40) of claim 4, capable of stretching in multiple directions of greater than 5% and less than or equal to 25% under forces of between greater than or equal to 50 grams and less than or equal to 2000 grams. 7. The multidirectionally stretchable absorbent article (40) of claim 4, in which the omnidirectionally stretchable absorbent core (42) comprises a laminate comprising knit layers of nylon, polyester and acrylic materials. 8. The multidirectionally stretchable absorbent article (40) of claim 4, having a longitudinal extensibility under a first force measured along a longitudinal centerline, and a diagonal extensibility and a second force measured along a line forming an angle of less than or equal to 45º with the longitudinal centerline, wherein the first force required to stretch the absorbent article (40) longitudinally is greater than the second force required to stretch the absorbent article (40) diagonally.